They might be about to join together in holy matrimony, but that doesn't mean Meghan Markle and Prince Harry will be joining their finances too.

The engaged pair reportedly won’t be getting a joint bank account any time soon – and it’s not because Harry refuses to share his estimated worth of £30 million.

It’s actually all to do with tax.

As an American citizen, Meghan will have to pay the United States income tax for the three years it takes her to become a British citizen.

Meghan Markle won't be able to split a bank account with Prince Harry (Image: PA)

Marlene Koenig, a royal expert, told The Sun: “Even when married to a member of the British royal family, as long as she remains a US citizen she will have to pay income tax.

“If she has investments in the United States, say for example a retirement plan that she set up, if that’s making money, she would have to pay up.

“This is even on money earned outside the United States. If she receives money from her husband or his family, and that’s considered income, she would have to pay income tax on that."

So Harry can’t share the wealth – unless Meghan don’t mind it being taxed to high heaven.

It's not that Harry's being tightfisted... honestly (Image: REX/Shutterstock)

The star - who earned more than £36,000 per episode of Suits and is thought to be worth around £4million - will likely also have to fill out a United States form 8938 if she has more than £221,529 in assets per tax year.

And that form will reveal the ins and outs of her finances, potentially exposing details of the royal family’s assets in the process.

The pair are due to marry in May this year (Image: Alexi Lubomirski/Getty)

Marlene adds: “You can be sure that those at Buckingham Palace and those who run the accounts are looking very carefully at all of this to make sure that the royal family’s money does not get reported to the IRS!”

Prince Harry isn’t currently publicly funded and instead lives off a trust fund from his late mother, Princess Diana.

He splits the annual £3.5million payout with his brother William and the Duchess of Cambridge.